1. Technical Field
The invention relates to a power supply apparatus. Particularly, the invention relates to a power supply apparatus in which a bleeder resistor is omitted to decrease energy loss.
2. Related Art
A main effect of a power supply apparatus is to convert an alternating current (AC) input power with a high voltage and low stability that is provided by a power company into a direct current (DC) output power with a low voltage and high stability and suitable for the use of various electronic devices, and the DC output power is provided to electronic devices such as computers, office automation equipment, industrial control equipment, and communication equipment for usage.
In the conventional power supply apparatus, an electromagnetic interference (EMI) filter is generally disposed in a front-end stage, and an AC safety capacitor in the EMI filter is used to filter noises probably existed in an AC signal. As the capacitor has a characteristic of storing electric energy, in the structure of the conventional power supply apparatus, a bleeder resistor is further configured in the EMI filter to connect the AC safety capacitor in parallel, such that when an AC power of the power supply apparatus is turned off, the AC safety capacitor can discharge the electric energy through the bleeder resistor to avoid a risk of electric shock of a user. However, the bleeder resistor may cause an extra power loss during the operation of the power supply apparatus.